Add PNG save support

TODO.org

@@ -152,11 +152,11 @@ dependent on the chart's size (currently, for the big chart it's
 
 * Regiomontanus import                                          :version_2.0:
 
-* Chart export as different image types [2/3]                   :version_1.0:
+* Chart export as different image types [3/3]                   :version_1.0:
 
   - [X] SVG
   - [X] JPEG
-  - [ ] PNG
+  - [X] PNG
 
   Other formats supported by GDK-PixBuf are considered useless, and
   most people should be able to open these types.

src/ag-chart.c

@@ -2039,6 +2039,15 @@ ag_chart_export_jpg_to_file(AgChart        *chart,
     ag_chart_export_to_image(chart, file, theme, "jpeg", err);
 }
 
+void
+ag_chart_export_png_to_file(AgChart        *chart,
+                            GFile          *file,
+                            AgDisplayTheme *theme,
+                            GError         **err)
+{
+    ag_chart_export_to_image(chart, file, theme, "png", err);
+}
+
 void
 ag_chart_set_note(AgChart *chart, const gchar *note)
 {

src/ag-chart.h

@@ -110,6 +110,11 @@ void ag_chart_export_jpg_to_file(AgChart        *chart,
                                  AgDisplayTheme *theme,
                                  GError         **err);
 
+void ag_chart_export_png_to_file(AgChart        *chart,
+                                 GFile          *file,
+                                 AgDisplayTheme *theme,
+                                 GError         **err);
+
 void ag_chart_set_name(AgChart     *chart,
                        const gchar *name);
 

src/ag-window.c

@@ -922,6 +922,7 @@ ag_window_export_image(AgWindow *window, GError **err)
                                      NULL);
     gtk_file_chooser_add_filter(GTK_FILE_CHOOSER(fs), filter_svg);
     gtk_file_chooser_add_filter(GTK_FILE_CHOOSER(fs), filter_jpg);
+    gtk_file_chooser_add_filter(GTK_FILE_CHOOSER(fs), filter_png);
     gtk_file_chooser_set_filter(GTK_FILE_CHOOSER(fs), filter_svg);
     gtk_dialog_set_default_response(GTK_DIALOG(fs), GTK_RESPONSE_ACCEPT);
     gtk_file_chooser_set_local_only(GTK_FILE_CHOOSER(fs), FALSE);
@@ -953,6 +954,9 @@ ag_window_export_image(AgWindow *window, GError **err)
             } else if (filter == filter_jpg) {
                 extension = ".jpg";
                 save_func = &ag_chart_export_jpg_to_file;
+            } else if (filter == filter_png) {
+                extension = ".png";
+                save_func = &ag_chart_export_png_to_file;
             } else {
                 g_warning("Unknown file type");
                 gtk_file_chooser_set_filter(GTK_FILE_CHOOSER(fs), filter_svg);

src/astrognome.c

@@ -44,6 +44,7 @@ GtkFileFilter *filter_chart = NULL;
 GtkFileFilter *filter_hor   = NULL;
 GtkFileFilter *filter_svg   = NULL;
 GtkFileFilter *filter_jpg   = NULL;
+GtkFileFilter *filter_png   = NULL;
 GtkTreeModel  *country_list = NULL;
 GtkTreeModel  *city_list    = NULL;
 GHashTable    *xinclude_positions;
@@ -117,6 +118,11 @@ init_filters(void)
     gtk_file_filter_add_pattern(filter_jpg, "*.jpe");
     gtk_file_filter_add_pattern(filter_jpg, "*.jpeg");
     g_object_ref_sink(filter_jpg);
+
+    filter_png = gtk_file_filter_new();
+    gtk_file_filter_set_name(filter_png, _("PNG image"));
+    gtk_file_filter_add_pattern(filter_png, "*.png");
+    g_object_ref_sink(filter_png);
 }
 
 static int

src/astrognome.h

@@ -33,6 +33,7 @@ extern GtkFileFilter    *filter_chart;
 extern GtkFileFilter    *filter_hor;
 extern GtkFileFilter    *filter_svg;
 extern GtkFileFilter    *filter_jpg;
+extern GtkFileFilter    *filter_png;
 extern GtkTreeModel     *country_list;
 extern GtkTreeModel     *city_list;
 extern const GswePlanet used_planets[];